Sexual cycle of Cryptococcus neoformans var. grubii and virulence of congenic a and alpha isolates.

Journal Article (Journal Article)

Cryptococcus neoformans is a human-pathogenic fungus that has evolved into three distinct varieties that infect most prominently the central nervous system. A sexual cycle involving haploid cells of a and alpha mating types has been reported for two varieties (C. neoformans var. neoformans, serotype D, and C. neoformans var. gattii, serotypes B and C), yet the vast majority of infections involve a distinct variety (C. neoformans var. grubii, serotype A) that has been thought to be clonal and restricted to the alpha mating type. We recently identified the first serotype A isolate of the a mating type which had been thought to be extinct (strain 125.91). Here we report that this unusual strain can mate with a subset of pathogenic serotype A strains to produce a filamentous dikaryon with fused clamp connections, basidia, and viable recombinant basidiospores. One meiotic segregant mated poorly with the serotype A reference strain H99 but robustly with a crg1 mutant that lacks a regulator of G protein signaling and is hyperresponsive to mating pheromone. This meiotic segregant was used to create congenic a and alpha mating type serotype A strains. Virulence tests with rabbit and murine models of cryptococcal meningitis showed that the serotype A congenic a and alpha mating type strains had equivalent virulence in animal models, in contrast to previous studies linking the alpha mating type to increased virulence in congenic serotype D strains. Our studies highlight a role for sexual recombination in the evolution of a human fungal pathogen and provide a robust genetic platform to establish the molecular determinants of virulence.

Full Text

Duke Authors

Cited Authors

  • Nielsen, K; Cox, GM; Wang, P; Toffaletti, DL; Perfect, JR; Heitman, J

Published Date

  • September 2003

Published In

Volume / Issue

  • 71 / 9

Start / End Page

  • 4831 - 4841

PubMed ID

  • 12933823

Pubmed Central ID

  • PMC187335

International Standard Serial Number (ISSN)

  • 0019-9567

Digital Object Identifier (DOI)

  • 10.1128/IAI.71.9.4831-4841.2003


  • eng

Conference Location

  • United States